Color printing devices, such as, for example, ink-jet printers operate by applying small drops of ink to a print media (e.g., paper), thereby forming dots. Different colored dots are combined to form various desired colors for pixels that are being printed. By way of example, certain ink-jet printers utilize six different colors of ink, namely, dark Cyan (C), light cyan (c), dark Magenta (M), light magenta (m), yellow (Y), and black (K). Some ink-jet printers use fewer color inks, e.g., just four C, M, Y and K ink, while still others may use more than six color inks.
The inks are typically supplied by ink pens having several nozzles, which can be selectively controlled to eject drops of ink onto the print media. The ink pens are typically arranged in a print pen carriage that is moveably controlled by a transport mechanism such that a swath of color can be applied to a portion of the print media by selectively controlling the ink pens moving in relation to the print media.
Certain printing devices are configured to print bi-directionally. This means, for example, that swaths may be printed as the carriage of pens moves across the print media from a right hand side to a left hand side and then back across the paper from the left hand side to the right hand side. This bi-directional movement is then continued on down the print media, as needed to print the desired content.
Some bi-directional printing devices are configured to perform multi-pass printing, wherein several overlapping swaths are applied to an area of the print media in a sequential and selective manner. As such, a combination of inks in the form of layered dots may be employed to render colors in the resulting print.
One common use for such multi-pass printing processes is in the printing of photographic-like quality images. By way of example, certain conventional ink-jet printers can be configured to perform up to eight or more passes over an area of the print media during which a plurality of dots may be formed to represent each pixel in content being printed. To increase the visual quality of the resulting print, especially when the content includes images and graphics, special photographic quality inks and/or special photographic print media may be used.
Improvements have been made over the past few years in the inks and print media that are available today. Many of these improvements have been directed towards either improving or conversely compromising the dot gain of all of the color inks in an ink set. The dot gain (e.g., how much an ink drop grows compared to the initially wetted area) can be either improved or compromised by either changing the properties of the inks and/or the properties of the print media. One might seek to improve or increase the dot gain to support the printing of images, wherein more diffused dots tend to provide for a more photographic-like image quality. Conversely, one might seek to compromise or reduce the dot gain to improve the visibility and/or definition of an edge or object definition, for example, as might be advantageous in printing text and other lines.
Consequently, printing devices, processes, inks and/or media have tended to focus on only one of these printing goals. This is not always accomplished without some complication being introduced. One particular complication can be seen in the use of more aggressive, high dot gain inks (e.g., inks having highly penetrating solvents and surfactants), which may damage parts of the printing device and/or make the printer more difficult to service as the ink almost inevitably comes in contact with other materials in the printing device.
For these and other reasons, it would be beneficial to have methods and apparatuses that support both of these above-mentioned seemingly juxtaposed printing goals without necessarily requiring more improvements to either the inks and/or print media.